By: Tanishtha Nath
Cloning is often thought of as an exotic, unnatural process, but what exactly is cloning? Most people think that to be a clone means to have the same phenotypic properties as another organism, which is incorrect. In reality, clones are organisms that have identical or extremely similar DNA. An example of this is seen in identical twins; as the name states, they are identical not because they look the same, but because they share the same DNA. This falls under the category of naturally occurring clones, but artificial cloning also exists, and this is where biotechnology comes into play.
There are three main types of artificial cloning:
1. Gene cloning
The purpose of gene cloning is to make multiple copies of a certain piece of DNA. The first step of gene cloning is adding the DNA fragment that is being cloned to a plasmid—a circular piece of DNA—which makes recombinant DNA. Then the recombinant plasmid is inserted into a bacteria, which carries the plasmid as it grows. Once that bacteria reproduces, the original gene is passed to its offsprings, therefore making copies of the gene. What exactly is the purpose of doing this? For scientists to undergo certain experiments, multiple copies of genes are needed. Additionally, gene cloning is used when DNA encodes an important protein, such as the insulin gene. Today, a large percentage of the world’s insulin supply is synthesized by yeast and bacteria.
2. Reproductive cloning
Reproductive cloning is when copies of whole organisms are made. This includes the famous sheep, Dolly, who was cloned from an adult sheep through a process called nuclear transplantation. The first step in cloning Dolly was to acquire somatic cells from a mammary cell donor. Then, an egg cell was removed from a different donor, and the nucleus was removed from that cell to be fused with the somatic cells. As the fused cell grew, it formed an early embryo which was implanted in the uterus of a third sheep, the surrogate mother. Afterward, the surrogate gave birth to a lamb that was genetically identical to the mammary cell donor. Although it is still commonly used, reproductive cloning raises concerns about the health and well-being of cloned organisms, as many such organisms age more quickly or are more prone to disease than natural organisms.
3. Therapeutic cloning
Therapeutic cloning is extremely similar to reproductive cloning, however, the embryos are never put in a womb. The intent of therapeutic cloning is to extract stem cells from cloned embryos, which can then be used in experiments that include creating or replacing tissues. Research regarding this process is relatively slow compared to reproductive cloning.
These three forms of cloning have made tremendous strides in recent years, and the possibility of cloning humans has even been floated. Nevertheless, human cloning involves many risks, whether it be psychological, social, or physiological, making the practice universally condemned. Further, discussions regarding the ethics behind modern cloning and whether or not it should be continued are also occurring. We encourage you to dive deeper into the world of cloning, and to share your findings with us!
Khan, Academy. “Overview: DNA Cloning (Article).” Khan Academy, Khan Academy, https://www.khanacademy.org/science/ap-biology/gene-expression-and-regulation/biotechnology/a/overview-dna-cloning.
National Geographic, Society. “Cloning.” National Geographic Society, 8 July 2019, https://www.nationalgeographic.org/encyclopedia/cloning/#:~:text=Cloning%20is%20a%20technique%20scientists%20use%20to%20make%20exact%20genetic,themselves%20each%20time%20they%20reproduce.
National Human Genome, Research Institute. “Cloning Fact Sheet.” Genome.gov, 2020, https://www.genome.gov/about-genomics/fact-sheets/Cloning-Fact-Sheet.
Reece, Jane B., et al. “Chapter 20: DNA Tools and Biotechnology.” Campbell Biology, Pearson, Boston, 2014, pp. 424.
“Reproductive Cloning.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., https://www.britannica.com/science/cloning/Reproductive-cloning.
Comments